■ What are OM and OS type fiber optic cables?

Fiber optic cables used in telecommunication are broadly categorized into two types –  Multimode fiber and Single-mode fiber cables. The multimode fiber cable is prefixed with 'OM' and the Single-mode fiber cable is prefixed with 'OS'.

In ISO/IEC 11801 and EIA/TIA standards five types of Multimode – OM1, OM2, OM3, OM4 & OM5 and two types of Single-mode – OS1 & OS2  fibers are mentioned. In all the standards the OM/OS system applies to cabled optical fiber,  and the cabling standards deal with cable and connecting hardware. 

ISO/IEC 11801 and  24702 make it clear that the nomenclatures OM1, OM2, OM3, OS1, and OS2 relate to cable transmission performance whereas the BS EN 50173 series makes it even clearer by describing the OM/OS nomenclature as "optical fiber cable categories".

■ What are the differences between OM and OS-type cables?

Technical difference

The main difference between OM and OS type cables is in core diameter with OM multimode fibers has a much larger core size. Two types of OM cables with core diameters of 50 microns and 62.5 microns are specified. The large core gives OM cables a higher "light-gathering"

Light Source—Multimode devices usually use a LED or laser as a light source. While single mode devices use a laser, or laser diode, to produce light injected into the cable.

capacity compare to OS cables. In practical terms, the larger core size simplifies connections and allows the use of lower-cost light sources such as light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) operating at 850 nm and 1300 nm. OS cables used in telecommunications operate mainly at 1310 or 1550 nm wavelengths and require more expensive laser sources. 

Compared to OS cables, the –bandwidth distance product (represented as MHz.km) of OM fibers is low because the larger core-size supports more than one propagation mode; hence it is limited by modal dispersion.

Practical Difference

Distance—Light travels a longer distance inside single mode cable than it does inside multimode. So multimode fiber is suitable for short haul application, allowing transmission distances of up to about 550m at 10Git/s. When distance is beyond 550m, single mode fiber is preferred.

Price—Multimode fiber usually cost less than single mode fiber.

Bandwidth—The bandwidth of single-mode is higher than multimode as much as 100,000 GHz.

■ Comparison between different types of OS fiber optic cables

OS1:

Optical Singlemode Fiber, 1.0 dB/km for OS1, with speeds from 1-10Gb/s at distances up to 2km. Mostly used as a tight buffer fiber for indoor use.

OS2: 

Optical Singlemode Fiber. The typical attenuation is 0.40 dB/km at 1310nm and 0.30 dB/km at 1550nm. At Gigabit speeds, the signal can normally travel up to 25km on this fiber (at 1310nm) and up to

80km at 1550nm. At 10Gb/s speeds the distance is a minimum of 5-10km at 1310nm and 30-40km at 1550nm. Mostly used as loose buffered fiber for outdoor use.

About the Cable Construction and the Differences Category OS1 and Category OS2 are the two types of cable construction. Category OS1 is recommended

for internal tight buffered cable construction, and Category OS2 is recommended for loose tube or blown

fiber solution. The loose tube cable is made from optical fiber and gives the best installed performance of 0.4dB per km. Category OS1 cable is designed for use in internal situations where the maximum distance is 2km. The 

cable type will allow speeds of over 1 to 10 Gb/s Ethernet. By contrast, category OS2 cable is designed

for maximum distance of 5km to 10km.

Attenuation comparison between different OS fiber optic cables

■ OM1 vs OM2 vs OM3 vs OM4 vs OM5: What's the Difference? 

Multimode fiber (MMF) is a kind of optical fiber mostly used in communication over short distances, for example, inside a building or for the campus. Multimode fiber optic cable has a larger core, typically 50 or 62.5 microns that enables multiple light modes to be propagated. Because of this, more data can pass through the multimode fiber core at a given time. The maximum transmission distance for MMF cable is around 550m at the speed of 10Git/s. It can transmit farther at lower data rates, such as going about 2km at 100Mb/s.

OM1: 

For optical multimode fiber with 200/500MHz*km overfilled launch (OFL) bandwidth at 850/1300nm (typically 62.5/125um fiber which is now obsolete.)

OM2: 

Type A1a.1 , for optical multimode fiber with 500/500MHz*km OFL bandwidth at 850/1300nm (typically 50/125um fiber)

OM3: 

Type A1a.2, for laser-optimized 50um fiber having 2GHz*km effective modal bandwidth (EMB, also known as laser bandwidth), designed for 10 Gb/s transmission.

OM4: 

Type A1a.3, for laser-optimized 50um fiber having 4.7GHz*km EMB bandwidth designed for 10Gb/s, 40 Gb/s, and 100 Gb/s transmission.

OM3 vs OM4

OM4 fiber has been on the market since 2005, sold as premium OM3 or OM3 fiber. The OM4 designation standardizes the nomenclature across all manufacturers so that the customer has a clearer

idea of the product that they are buying. OM4 is completely backwards compatible with OM3 fiber and shares the same distinctive aqua jacket. OM4 was developed specifically for VSCEL laser transmission

and allows 10 Gigabits/second link distances of up to 550 Meters (compared to 300 Meters with OM3). The effective modal bandwidth for OM4 is more than double that of OM3 (4700 MHz.km for OM4 vs 2000 MHz.km for OM3).

While OM3 fiber will still be future proof in most applications, allowing speeds of 10Gb/s up to 100Gb/s, OM4 fiber offers users longer length distances and more bandwidth for optical budgets.

OM5: 

For laser-optimized for 50µm fiber greater than 28GHz*km EMB bandwidth designed for 40 Gb/s, and 100 Gb/s transmission.

Physical Difference

Physical difference mainly lies in diameter, jacket color, optical source and bandwidth, which is described in the following table.

Practical Difference

Multimode fibers are able to transmit different distance ranges at various data rate. You can choose the most suited one according to your actual application. The max multimode fiber distance comparison at different data rate is specified below.

■ Fiber Optic Patch Cord Product List by Fiber Type

Notes

· The website primarily organizes products by connector type (e.g., SC, LC, FC) and mode (single-mode or multimode) rather than explicitly by OS1, OS2, OM1, OM2, OM3, OM4, or OM5. Fiber types are inferred from descriptions, such as core/cladding sizes (9/125µm for single-mode, 50/125µm or 62.5/125µm for multimode) and jacket colors (yellow for single-mode, orange for OM1/OM2, aqua for OM3/OM4, lime green or aqua for OM5).

· Single-mode patch cords are generally compatible with both OS1 and OS2, with OS2 offering better performance for longer distances. Multimode patch cords are categorized by OM standards, with OM1–OM5 indicating increasing bandwidth and distance capabilities.

· Some products (e.g., OM4 and OM5) are mentioned in descriptions but not linked to dedicated product pages. In such cases, the main patch cord page is provided as the link, as it contains references to these fiber types.

For precise specifications or custom configurations, Zion communication offers customization.

James is a technical manager and associate at Zion Communication. 

Specializes in Optical Fiber communications,  FTTH Solutions, 

Fiber optic cables,  ADSS cable, and ODN networks.

james@zion-communication.com

+86 13777460328